Compliant foil bearings are often used in high performance applications requiring tolerance of high temperature and speed, for example, gas turbine engines. Such bearings exhibit superior operational and durability characteristics as compared to bearings which require liquid lubrication and liquid cooling systems.
One problem experienced in known compliant foil bearing systems has been that, while it is advantageous to minimize the thickness of the foil bearing in order to render it sufficiently compliant to conform to the supported member uniformly under all conditions, such thin foils exhibit a reduced load-bearing capacity and ability to control oscillatory motion.
Another problem relates to the phenomenon that a high-speed shaft tends to orbit about the geometric center of its bearing. The amplitude of oscillation is maximized at certain critical speeds. In order to control this oscillation, it is desirable to provide substantial Coulomb damping in the bearing assembly. This problem is especially critical in the case of small journal bearings in which only limited space is available for the bearing assembly. Proper control or elimination of high-speed instability will permit the bearing to operate to the burst speed of the rotating assembly.